Flood protection - Nature knows best

Nature Climate Change

July 15, 2013

Natural coastal habitats shield people and property from sea-level rise and storms, according to a study published in Nature Climate Change this week. The paper presents the first country-wide map of risk reduction provided by natural habitats in the United States, and indicates where conservation and restoration of reefs and vegetation have the greatest potential to protect coastal communities.

Globally, coastal flooding and sea level are expected to increase significantly by the mid twenty-first century, and in the United States - where 23 of the nation's 25 most densely populated counties are coastal - large numbers of people and their property are already at risk. The traditional approach to protecting towns and cities has been to engineer shorelines to provide protection from the elements and although these types of solutions are necessary and desirable in some contexts, they can be expensive to build and maintain, degrade water quality and reduce fish stocks. Over the past decade, coastal protection efforts have begun to consider conservation and restoration of coastal habitats, but tools to evaluate the potential role of natural defence mechanisms remain limited.

Katie Arkema and colleagues modelled the complete loss of natural protection to identify where these habitats reduce the exposure of people and property to hazards. They predict that habitat loss would double the extent of coastline that is highly exposed to storms and sea-level rise, making an additional 1.4 million people now living within 1 km of the coast vulnerable. The number of poor families, elderly people and the total property value exposed to hazards are predicted to double if protective habitats are lost.

The authors suggest that strategies incorporating both habitat conservation and engineered approaches should be investigated further to reduce damages caused by coastal flooding and rising sea level.